Ante-Nicene Fathers, Vol IX:
Origen's Commentary on the Gospel of Matthew.: Chapter XLIII

43.  Relation of Moses and Elijah to Jesus.  The Injunction of Silence.

But after these things it is written that, when they heard the voice from the cloud bearing testimony to the Son, the three Apostles, not being able to bear the glory of the voice and power resting upon it, “fell on their face,” 5816 and besought God; for they were sore afraid at the supernatural sight, and the things which were spoken from the sight.  But consider if you can also say this with reference to the details in the passage, that the disciples, having understood that the Son of God had been holding conference with Moses, and that it was He who said, “A man shall not see My face and live,” 5817 and taking further the testimony of God about Him, as not being able to endure the radiance of the Word, humbled themselves under the mighty hand of God; 5818 but, after the touch of the Word, lifting up their eyes they saw Jesus only and no other. 5819   Moses, the law, and Elijah, the prophet, became one only with the Gospel of Jesus; and not, as they were formerly three, did they so abide, but the three became one.  But consider these things with me in relation to mystical matters; for in regard to the bare meaning of the letter, Moses and Elijah, having appeared in glory and talked with Jesus, went away to the place from which they had come, perhaps to communicate the words which Jesus spake with them, to those who were to be benefited by Him, almost immediately, namely, at the time of the passion, when many bodies of the saints that had fallen asleep, their tombs being opened, were to go to the city which is truly holy—not the Jerusalem which Jesus wept over—and there appear unto many. 5820   But after the dispensation in the mountain, when the disciples were coming down from the mountain in order that, when they had come to the multitude, they might serve the Son of God concerning the salvation of the people, Jesus commanded the disciples saying, “Tell the vision to no man until the Son of man rise from the dead.” 5821   But that saying, “Tell the vision to no man,” is like that which was investigated in the passage above, when “He enjoined the disciples to tell no man that He was the Christ.” 5822   Wherefore the things that were said at that passage may be useful to us also for the passage before us; since Jesus wishes also, in accordance with these, that the things of His glory should not be spoken of, before His glory after the passion; for those who heard, and in particular the multitudes, would have been injured when they saw Him crucified, who had been so glorified.  Wherefore since His being glorified in the resurrection was akin to His transfiguration, and to the vision of His face as the sun, on this account He wishes that these things should then be spoken of by the Apostles, when He rose from the dead.

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Footnotes

Matt. xvii. 6.

Exod. xxx. 20.

1 Pet. v. 6.

Matt. xvii. 8.

Matt. 27:52, 53.

Matt. xvii. 9.

Matt. xvi. 20.